Connection-based synchronization

Some synchronization technologies rely on the presence of a continuous, or at least almost continuous, connection between
the databases. Through this connection, the two databases conduct an ongoing dialog. These types of systems excel at replicating
changes quickly. Given enough resources and channel capacity, synchronization can occur reliably with a lag time of no more
than a few seconds.

The main drawback of this type of system is that a reliable, continuous connection can be expensive to maintain. This restriction
makes connection-based technologies suited to replication between two large, fixed databases. In environments where the remote
computers are mobile or are only occasionally connected, session-based (MobiLink) or message-based (SQL Remote) technologies
provide more flexible solutions.